Subject to the application, sensors tend to be integrated on semiconductor substrates. This kind of manufacturing is beneficial in that the size of the sensors can significantly be reduced compared to discrete type sensors, and such sensors can be arranged together with electronic circuitry integrated on the same semiconductor substrate which circuitry may include functions acting on a signal delivered by the sensor such as amplification, evaluation, etc.
An integrated chip comprising a sensor is called sensor chip in the following. In such sensor chip, the sensor and possibly electronic circuitry are arranged at a front side of a substrate. The circuitry may be formed by CMOS processing, and the building and/or arranging of a sensing element of the sensor on the front side may be implemented in a way compatible to CMOS processing. When such sensor chip needs to be integrated into a processing system, the sensor chip typically will be connected to circuitry residing on a different circuit board, such as a printed circuit board, for example. A preferred way for mounting a sensor chip to such circuit board is a technique called flip chip mounting in which the sensor chip is flipped such that its front side containing the sensing element and the circuitry faces the circuit board and is electrically connected to it. The electrical connection typically is achieved between contact pads arranged at the front side of the sensor chip and contact pads arranged on the circuit board and solder material in between.
However, now the sensing element faces the circuit board which may not be preferred for various reasons: In case the sensor shall detect a quantity of a measure in a medium in the environment of the sensor, such medium may not have sufficient access to the sensing element for the reason of its arrangement facing the circuit board. In addition, and even worse, the sensing element may be affected during handling, and specifically when mounting/soldering the sensor chip to the circuit board, e.g. when applying a solder forming flux.